thebluerx7

hey,i have a first gen rx7.



13bre un-opened import block(52000km,tested 130psi compression)

70mm turbo (80mm rear)

ltx8

water injection

cdi's

550/1700 injectors

044 pump

etc etc etc.



i have set it up running 10deg of total advance at 25psi boost,running 10.5-11.0afrs(only at about 8g its actually at 11.0) on 98 octane fuel.i and others estimate in the vicinity of 500-540rwhp (dyno dynamics).it has that fuel sytem maxed out anyway



the car was goin great for 2 weeks at this power level with consistent performance and afrs etc even in middle of the day(actually about 10.3afr in middle of day),then the other night on 11deg ambient ,the engine let go and lost all comp on rear rotor .i am stripping motor down tomorrow night and suspect major apex seal failure.



it was all same running perameters and afrs on pervious run were 10.5-10.8's,so still fine.



do u guys think same as me and it just is old fatigued metal seals etc in motor just let go?



whats ur thoughts?



thanks

jason

thebluerx7

forgot to add i run greddy pro rotary re11 plugs

j9fd3s

yeah at that boost level it might have just been old...

Old Grey

Never had much luck with factory apex seals over 300rwhp, a little too much timing or slightly lean and the seal will sag , blue mark in the centre like someone heated it with a oxy torch.



500-540rwhp sounds high for 10.5 in a light car

thebluerx7

the seals in it are silver everywhere except right at the corner edge where they broke off 2 tips of the apex seals,otherwise they are silver.no heat street except at breakage point.



i dunno what power it made,was over 450rwhp anyway.

j9fd3s

that corner is the weakest part of the seal. it either broke due to seal growth cause it was too hot, or it was detonating a little.

Old Grey

Fairly common for 2mm factory apexs

bumpstart

which forum will you not like my experienced unbiased answer on ?

i have raced a 3.2 lpm fuel system ( 3 bar rating ) at 3.5 bar on a ported hybrid 6 port turbo with 9.4 comp

and 18 psi and crude water injection in 1999

i wouldn't think that's all that much more than 350 rwhp at best

( 1999 is pre dyno days in most Perth rotor shops )

but to the fail limits of undowelled s5 6 port plates

and s5 stat gears and standard apex seals ( same fails as yours )

and corner seals and HP capable of twisting the crank

i also tune my own, and have tuned, and trouble shoot many of Perth's rotors , haltech and microtech

mainly those disillusioned with the service from the limited shops



i am not rice racing , and i dont sell products or have anything to gain in giving you my opinion

rather would like to see you avoid the repeat performance





here is my unbiased opinion -



your fuel system is maxed, probably with injectors beyond a duty cycle they can be consistent at

this is checked with AFR during the day , after engine bay and intake air temps have risen

and also after some driving that has steadied out system charging and volts



microtechs do not have injector dwell , or volt compensation adjust for its injector maps

it assumes perfect world , same volts every time

most rx7 charging systems and wiring are marginal at 70 A to 80 A for a system with more injectors and pumps

( and ICE )



microtech, hence, is notorious for changing its mixes slightly according to volts on the day

they are known to sometimes run leaner when the lights are on !!!!



fuel pumps also DO NOT like lower voltages in terms of output



add to that, the low ambient conditions in comparison to the tested days

the density is related to the temperature,

so cold air greatly affects the mass of oxygen in the chamber

and hence cylinder filling and effective compression ratio



- several lean trims stacked on top of that already stressed and possibly erratic at those duty cycles injector flow rates !

chuck in some passengers, or a hill , ping city, chipped apex long piece and flattened corner seals quicker than you can react





you need to upgrade the wiring and charging system to ensure more stability at all conditions with that ECU

you also need to upgrade the fuel system so as not to be beyond 80 % duration at any time

and check the wiring at the pump !

also check for a fuel reg thats prone to spiking or pulsing

thebluerx7

ok,thanks bumpstart.where was that reply on ausrotary.



anyway,i have a mixture meter in my car full time,and in the exact conditions of the night when it happened ,the pass b4 it was running 10.3afrs.but i understand what u mean and i am adding an 044 pump to the system for its next setup.during hot day under same loads from 2nd to 5th gear it still reads at its absolute leanest reading 11.0afr,and on really cold night there can sometimes be 10.0's flat out say in 3rd gear alone.



my charging system is very good,its a 90A s6 alternator,has feed cables to battery and starter and earths that are literaly welding cable from welding supplies shop,which are rated at several hundred amps of current,so i have no issues there.the whole system ecu/etc has all been redone by me as i didnt trust the previous wiring,so its all excellent and well above spec for the current draw of each system



i have 6mm wire to the fuel pump and have no voltage drop to the pump at all currently,my fuel reg is rock solid on dyno previously and is repeatable time and time again over the years.



and yes,mine does run leaner with lights on,mine was actually tuned with lights on,and does run richer in the day time even though its hotter.



so beleive it or not,its actually had all those issues seen to with this setup,but only thing i will be doin this time is running ra super seals and stock rebuild with correct clearances,and another 044 pump,and maybe 1000cc primaries,thats it,there is no reaosn why it shoudl not last after that imo.



what do u think?

j9fd3s

i think thats about right, at big boost it doesnt have to be off much, and just to clip a corner, it wasnt off much.